Directionally reversible rotary offset printing machine and wetting system therefor

ABSTRACT

At least two rollers are provided to form part of the wetting system, one being axially shiftable and forming a rubbing cylinder, and having a surface which can be wetted by ink, the other roller being in driven engagement with the rubbing cylinder, as well as the plate cylinder, and forming a wetting liquid transfer roller, the circumferential speed of the transfer roller being different from the circumferential speed of the plate cylinder with which it is in engagement. Preferably, the circumference of the rubbing cylinder is copper, or a plastic material capable of being coated by ink; the rubbing cylinder also, preferably, has a greater diameter than the transfer roller, and drives the transfer roller by frictional engagement.

I United States Patent 1 1 1111 3,890,898 Fischer 1 June 24, 1975 [54] DIRECTIONALLY REVERSIBLE ROTARY 3,467,008 9/1969 Domotor 101/148 X OFFSET PRINTING MACHINE AND 2:338 gorshingwn :12 Of 011 .4 WETTING SYSTEM THEREFOR 3,516,354 6/1970 11611111161161, 101/148 x [75] Inventor; Hermann Fischer, Augsbury, 3,594,255 7/1971 Budinger 101/148 UX Germany 3,688,694 9 1972 Preuss 101/148 1 3,759,175 9/1973 Alsop 101/148 [73] Assignee: Maschinenfabrik Augsburg-Nurnberg Primar E J R y xammer eed F1sher Aktlengeseuschaft Augsburg Attorney, Agent, or FirmF1ynn & Frishauf Germany [22] Filed: Dec. 26, 1973 [57] ABSTRACT [21] Appl. No: 427,788 At least two rollers are provided to form part of the wetting system, one being axially shiftable and forming a rubbing cylinder, and having a surface which can be [30] Forelgn Apphcatmn Pnomy Dam wetted by ink, the other roller being in driven engage- Jan. 16, 1973 Germany 2301879 ment with the rubbing cylinder, as we as the plate cylinder, and forming a wetting liquid transfer roller, [52] US. Cl 101/148; lOl/349 the circumferential Speed of the transfar roller being [51] lIlt.C|. B41F 7/26 different from the circumferential Speed of the plate [58] Fleld of Search 101/147, 148, 349, 350, Cylinder with which it i in g g Preferably, 101/206 207 the circumference of the rubbing cylinder is copper, or a plastic material capable of being coated by ink; [56] References Clted the rubbing cylinder also, preferably, has a greater di- UNITED ST S PATENTS ameter than the transfer roller, and drives the transfer 2,586,480 2/1952 Ras 101 147 roller by frictional engagement. 2,960,929 11/1960 Erzinger 101/147 3,094,065 6/1963 Roberts 10l/148 8 Clam, 2 D'awmg Flgures PATENTEIJJUN24 1915 8,880,888

RUBBER CYLINDERS L INK TRAIN 1 DIRECTIONALLY REVERSIBLE ROTARY OFFSET PRINTING MACHINE AND WETTING SYSTEM THEREFOR The present invention relates to rotary offset printing machines, and more particularly to such machines in which the direction of rotation is reversible, and to the wetting system therefor.

It has previously been proposed to arrange the wetting system, or wetting train used with rotary offset printing machines so that they engage either the plate cylinder, or the rubber blanket cylinder of the printing press, depending on the direction of rotation thereof (see, for example, German Pat. No. 1,61 1,197). In this arrangement, the location of the wetting roller system is so placed that, upon relocation of the wetting system when direction of rotation is changed, the wetting liquid is always applied in advance of ink. This wetting arrangement requires, however, sufficient space for its alternate location in the vicinity of the plate cylinder, and thus, unused space must be provided for, to permit shiftingof the wetting system.

It is an objectof the present invention to provide a wetting system for use with a reversible rotary printing press which is space-saving, does not require any dead space, and in which change in direction of rotation can be carried out without substantial relocation of elements in the printing press.

Subject matter of the present invention: Briefly, the wetting system is fixed in location within the printing press and has two wetting rollers or cylinders. One of the wetting rollers or cylinders is driven to rotate and additionally to axially reciprocate. Its circumferential surface is made of copper, or a plastic which can accept ink. The other cylinder is a transfer cylinder and is in frictional engagement with the driven rubbing cylinder. It is driven, by this frictional engagement, with a circumferential speed which differs from the circumferential speed of the plate cylinder, with which it is in engagement. The entire surface of the rubbing cylinder will have a uniformly distributed film of ink applied thereon, about which a film of wetting substance, typically water, is applied which will have uniform thickness and which is transferred by the transfer roller or cylinder, in accurately determined quantity by the engagement between the rubbing cylinder and the transfer roller, on the plate cylinder. The film of ink which occurs within the wetting system increases friction between the rubbing cylinder and the transfer roller, and thus slip between these two cylindrical elements is avoided. The speed at which the transfer roller is driven by the rubbing cylinder permits application of wetting substance to the plate cylinder even after inking thereof.

The invention will be described by way of example with reference to the accompanying drawings, wherein:

FIGS. 1 and 2 illustrate, in highly schematic form, the cylinder arrangements of a reversible rotary offset printing machine, FIG. 1 illustrating rotation of the rubber cylinders for downward feed of web material to be printed, and FIG. 2 illustrating the reverse direction of rotation, for upward feed of material to be printed.

Like elements have been given the same reference numerals in FIGS. 1 and 2; plate cylinder 1 is in contact with a rubber cylinder 2, the other rubber cylinder 2' being a counter-cylinder which may, or may not have an additional printing system in contact therewith for double-sided simultaneous printing. A paper web 20 is carried between the nip of the rubber cylinders 2, 2'. The ink application rollers 3, 4 directly engage the plate cylinder 1. Ink application rubbing cylinders 5, 7, 9 and intermediate rollers 6, 8, 10 directly, and indirectly, respectively, apply ink to the ink application rollers 3, 4. The intermediate rollers 10 and 8 are engaged, in dependence on the direction of rotation of the printing press, with the ink rubbing cylinder 9, for example by lateral shifting of rollers 10, and 8, respectively; upon such lateral shift, engagement of the intermediate rollers 6 and 8 (FIG. 1) will likewise be broken (compare FIGS. 1 and 2). The ink transfer cylinder 9 is directly, or indirectly contacted by a transfer roller 1 1, a lifting roller 12, an ink adduction roller 13 and an immersion roller 14. The immersion roller 14, which dips into ink held in an ink trough 15, applies ink over the ink adduction roller 13, the lifting roller 12, the transfer roller 11, to the ink rubbing cylinder 9. From the ink rubbing cylinder 9, the respective intermediate rollers 8 or 10, and 6, apply the ink, while being spread, to the upper rollers. The ink is eventually applied to the plate cylinder 1 through theremaining rollers 7, 5, 4, 3.

In the direction of rotation indicated in FIG. 1 the wetting system is located in advance of ink application with respect to direction of rotation; when the direction of rotation of FIG. 2 is selected, the wetting system is located behind the ink train, with respect to the direction of rotation of the plate cylinder 1. The wetting system has a transfer roller 16 with a rubber surface which is in contact with an axially movable rubbing cylinder 17. Axial shift of the rubbing cylinder is schematically indicated by arrow A. The rubbing cylinder 17 has a circumference which is made of copper, or a plastic material which can accept ink, or be coated by ink. Since a portion of the ink applied to the plate cylinder 1 is transferred to the transfer roller 16, and, hence on the rubbing cylinder 17, an essentially uniform ink film is applied on the circumferential surfaces of roller and cylinder 16, 17, after the machine has been operating. A wetting fountain system 19 applies an essentially uniform liquid film on the rubbing cylinder 17. This liquid film is measured, or split by the nip between the rubbing cylinder 17 and the rubberized transfer roller 16. Accurate, fine measurement of application of a liquid film is thus effected, for further transfer to the plate cylinder 1. Any other system of applying an essentially uniform film of wetting water, or similar liquid, to the rubbing cylinder 17 may be used.

The film of ink on the rubbing cylinder 17, and on roller 16 increases friction within the wetting system, so that roller 16 and rubbing cylinder 17 will have but little relative slip between each other. The rubbing cylinder 17, which reciprocates, is of larger diameter than the transfer roller 16. It is driven by means of a drive system, schematically shown at 18, driven by a motor M which is a variable speed motor, as schematically indicated by the arrow. Other variable speed drives may, of course, be used to permit variation of the speed of the rubbing cylinder 17. The transfer roller 16 is driven by frictional engagement with the driven rubbing cylinder 17. Transfer roller 16, in dependence on the speed of the rubbing cylinder 17, will have a speed which may be larger, or less than that of the plate cylinder 1. In ordinary use, the rubbing cylinder 17 will have a greater speed than the plate cylinder 1, so that any loss in circumferential speed of the transfer roller 16, due to the unavoidable surface deformation occurring in the nip between the rubbing cylinder 17 and the transfer roller 16, is compensated. The higher circumferential speed of the transfer roller 16 with respect to the plate cylinder 1 provides for cleaning of the plate cylinder 1 by the transfer roller 16, thus avoiding streaks, or toning of the surface of the plate cylinder. Thus, effective use of the wetting system is ensured, particularly if the direction of rotation is as in FIG. 2, that is, with wetting after ink application.

The wetting system in accordance with the present invention can be used with all types of rotary offset printing machines; it requires but little space within the printing machine particularly the space immediately adjacent the plate cylinder 1, which is necessary for accessibility for maintenance and cleaning and replacement is only little obstructed by the wetting system itself; changing the production runs of the printing press is thus facilitated.

I claim:

1. Directionally reversible rotary offset printing machine comprising a plate cylinder operable in either direction of rotation when printing;

inking means (3-15) having a fixed location with respect to the plate cylinder (1) and applying ink to the plate cylinder;

a wetting system 16-19) having a fixed location with respect to the plate cylinder (1), separate from the inking means, so that the relative position of the wetting system and of the inking means, with respect to the surface of the plate cylinder reverses upon reversal of the direction of rotation of the plate cylinder (1);

wherein the wetting system comprises at least two rollers, one of the rollers (17) being axially shiftable and forming a rubbing cylinder and having a surface capable of being coated by ink,

the other roller (16) forming a wetting liquid transfer roller having a rubberized surface and being lo-,

cated in frictional, rotation-transmitting engagement with the rubbing cylinder (17) and further engaging the plate cylinder (1),

the circumferential speed of said wetting transfer roller (16) being controlled by its engagement with the rubbing cylinder- (17 and differing from the circumferential speed of the plate cylinder (1);

means (M) positively drivinglthe shaft of the rubbing cylinder (17) so that the surface of the rubbing cylinder (.17) will be rotating at a circumferential speed differing from the surface of thecircumferential speed of the plate cylinder,'as well as being axially reciprocating;

and means (19) applying a wetting liquid to the surface of the rubbing cylinder (17) so that a fine film of wetting liquid will form over ink deposited on the surface of the rubbing cylinder by transfer from the plate cylinder (1) over the transfer roller (16), for application of said wetting liquid to the plate cylinder by the transfer roller (16) when driven by engagement of its ink-and-wetting liquid coated surface with the ink-and-wetting liquid coated surface of the rubbing cylinder (17).

2. Machine according to claim 1, wherein the'surface of the rubbing cylinder (17) is copper.

3. Machine according to claim 1, wherein the surface of the rubbing cylinder (17) comprises a plastic material being capable of being coated by'printing ink.

4. Machine according to claim 1, wherein the rubbing cylinder (17) has a larger diameter than the trans fer roller (16).

5. Machine according to claim 1, wherein the means (M) driving the rubbing cylinder (17) drive the rubbing cylinder at a speed which is variable.

6. Machine according to claim 5, wherein the speed of the rubbing cylinder (17) is set to provide a circumferential speed of the transfer roller (16), as driven by frictional engagement with the rubbing cylinder (17), which is less than the circumferential speed of the plate cylinder (1 7. Machine according to claim 5, wherein the speed I of the rubbing cylinder (17) is set to provide a circum- 

1. Directionally reversible rotary offset printing machine comprising a plate cylinder operable in either direction of rotation when printing; inking means (3-15) having a fixed location with respect to the plate cylinder (1) and applying ink to the plate cylinder; a wetting system (16-19) having a fixed location with respect to the plate cylinder (1), separate from the inking means, so that the relative position of the wetting system and of the inking means, with respect to the surface of the plate cylinder reverses upon reversal of the direction of rotation of the plate cylinder (1); wherein the wetting system comprises at least two rollers, one of the rollers (17) being axially shiftable and forming a rubbing cylinder and having a surface capable of being coated by ink, the other roller (16) forming a wetting liquid transfer roller having a rubberized surface and being located in frictional, rotation-transmitting engagement with the rubbing cylinder (17) and further engaging the plate cylinder (1), the circumferential speed of said wetting transfer roller (16) being controlled by its engagement with the rubbing cylinder (17) and differing from the circumferential speed of the plate cylinder (1); means (M) positively driving the shaft of the rubbing cylinder (17) so that the surface of the rubbing cylinder (17) will be rotating at a circumferential speed differing from the surface of the circumferential speed of the plate cylinder, as well as being axially reciprocating; and means (19) applying a wetting liquid to the surface of the rubbing cylinder (17) so that a fine film of wetting liquid will form over ink deposited on the surface of the rubbing cylinder by transfer from the plate cylinder (1) over the transfer roller (16), for application of said wetting liquid to the plate cylinder by the transfer roller (16) when driven by engagement of its ink-and-wetting liquid coated surface with the ink-and-wetting liquid coated surface of the rubbing cylinder (17).
 2. Machine according to claim 1, wherein the surface of the rubbing cylinder (17) is copper.
 3. Machine according to claim 1, wherein the surface of the rubbing cylinder (17) comprises a plastic material being capable of being coated by printing ink.
 4. Machine according to claim 1, wherein the rubbing cylinder (17) has a larger diameter than the transfer roller (16).
 5. Machine according to claim 1, wherein the means (M) driving the rubbing cylinder (17) drive the rubbing cylinder at a speed which is variable.
 6. Machine according to claim 5, wherein the speed of the rubbing cylinder (17) is set to provide a circumferential speed of the transfer roller (16), as driven by frictional engagement with the rubbing cylinder (17), which is less than the circumferential speed of the plate cylinder (1).
 7. Machine according to claim 5, wherein the speed of the rubbing cylinder (17) is set to provide a circumferential speed of the transfer roller (16), as driven by frictional engagement with the rubbing cylinder (17), which is greater than the circumferential speed of the plate cylinder (1).
 8. Machine according to claim 1, wherein the means applying a wetting liquid comprises a spray fountain system (19) applying a wetting spray on the rubbing cylinder (17). 